The commercial production and distribution of eggs for human consumption must assure that the eggs do not pose a health risk. However, eggs are typically contaminated with fecal matter, dirt and debris from broken eggs, feathers, remnants of a litter substrate, and the like. This contamination can lead to growth of harmful bacteria that can even penetrate the egg shell. While bacterial contamination is generally not visible, the presence of visible contamination on the egg surface is aesthetically displeasing to consumers and may hide cracks. In present commercial practice, eggs are quickly washed with a sanitizing solution within minutes of being laid.
The task of washing eggs is complicated by the need to remove contamination from the egg surface and the need to avoid damaging the egg shell. These two needs must be met simultaneously. A wash solution that cannot remove contamination is not suitable. For example, washing eggs with water alone is generally not suitable because water alone does a poor job of removing organic material from the egg shell surface or from cleaning up after an occasional broken egg. Similarly, a wash solution that damages the egg shell is not suitable either. For example, a strong bactericidal solution may damage the porosity of the egg shell.
A number of chemical approaches to egg washing have been tried. These chemical treatments include chlorine based disinfectants, quaternary ammonium salt disinfectants, peracetic acid solutions, surfactants and enzymes. However, these chemical treatments are not entirely suitable because these chemicals either quickly lose their activity, exhibit poor biodegradability themselves, require long contact times, provide insufficient removal of contaminants or damage the egg shell.
Therefore, there is a need for a method and system for washing egg shells that removes contamination efficiently without damaging the egg shells. It would be desirable for the method and system to exhibit extended activity, utilize compositions that are themselves biodegradable, provide effective removal of contaminants, and avoid damaging the egg shell. Furthermore, it would be desirable if the method and system could effectively remove physical contaminants adhering to the egg surface, but also could remove, destroy or prevent harmful bacterial contaminants or pathogens. Still further, it would be beneficial to have a method and system that could wash egg shells to remove stains or other visual defects and improve the yield of eggs that meet commercial standards.